Society and the Environment: Lost Populations: What Happened?

These large stone figures found on Easter Island were made by a civilization that has disappeared.

At various points in human history, entire populations have disappeared and left mysterious remains such as the Egyptian pyramids and the Anasazi pueblos in the southwestern United States. Why did these people and their civilizations disappear? Archeologists sometimes find evidence that environmental destruction was one of the reasons the populations disappeared.

Rapa Nui (Easter Island)
On the island of Rapa Nui, in the Pacific Ocean, the first European visitors were amazed to find huge stone heads that were kilometers from the quarries where the heads had been made. It seemed impossible that the islanders could have moved the heads. There were no horses, oxen, or carts on the island and there were also no trees, that could have been used as rollers to move the heads. The islanders were using grass and reeds to make fires because the island was barren grassland.

A Changed Environment
Researchers have now shown that Rapa Nui was very different when it was first colonized by Polynesians around 1200 CE. In the oldest garbage heaps on the island, archaeologists have found that one-third of the bones came from dolphins. To hunt dolphins, the islanders must have had strong canoes made of wood from tall trees. Pollen grains, which are used to identify plants, show that the island was once covered by a forest that contained many species found nowhere else in the world.

But by 1600 CE trees were rare and the Easter Island palm tree was extinct. The palm seeds were probably eaten by rats that the Polynesians had brought to the island. With the destruction of the forest, every species of native land bird also became extinct. With the added stress of disease carried by the European visitors, the local human population crashed. The people of Easter Island destroyed their environment by overusing its natural resources and introducing new species such as chickens and rats. The people were reduced from a complex civilization to a primitive lifestyle. Easter Island is a small-scale example of what ecologists worry could happen to Earth’s entire human population.